Hydraulic drive for trenching machine



May 8, 1962 J. F. I INDELL 3,032,994

HYDRAULIC DRIVE FOR TREZNCHING MACHINE Filed Deo. 14, 1959 2 Sheets-Sheet l MM WM@ May 8, 1962 J. F. LINDELL 3,032,994

HYDRAULIC DRIVE FOR TRENCHING MACHINE Filed Dec. 14, 1959 2 Sheets-Sheet 2 fri( fla/r? INVENTOR .1/,v ZM/05!! BQ@ fm Stes Patent free 3,032,994 HYDRAULIC DRIVE FOR TREN CHING MACHINE John F. Lindell, Newton, Iowa, assigner to Koehring Company, Milwaukee, Wis., a corporation of Wisconsin Filed Dec. 14, 1959, Ser. No. 859,329 Claims. (Cl. 60-52) The present invention relates generally to ditch digging machines or trenchers and concerns more particularly a hydraulic drive for spoil or dirt discharging conveyors in such machines.

Heavy duty trenching machines commonly employ digging wheels or digging ladders to remove the dirt or spoil, and the arrangement is such that this material is dumped onto a transverse conveyor which discharges it to one side or the other of the trench. It is conventional to drive the discharge yconveyor hydraulically, and it is quite desirable .to provide for adjustable speed control of the conveyor, as well as to provide hydraulic power for adjustably positioning the digging mechanism. Therefore, it is the general aim of this invention to provide an improved control system for a trenching machine aifording variable speed conveyor drive yand power positioning of the digging mechanism.

An object of the invention is to provide an improved hydraulic control system of the above type which is simple 4and economical since it avoids expensive variable delivery pumps or the need for three or more pumps to obtain varying capacities. Moreover, it is an object to provide a system of this character which utilizes a minimum number of directional valves and flow control valves, and which does not require expensive variable flow control valves.

It is also an object to provide a control system as described above which affords uninterrupted hydraulic drive of the discharge conveyor while permitting, simultaneously, power actuation of the digging mechanism positioning devices.

A further object of the invention is to provide a control system of the above character which is simple to operate in that a single control selects one of a plurality of available conveyor speeds.

It is another object of .the invention to provide a control system of the above type which is particularly etlicient in that little hydraulic iluid is required and power losses in the system are minimized.

Other objects and advantages of the invention will become apparent upon consideration of the following de.- tailed description and upon reference to the drawings, in which:

FIGURE 1 is -a perspective, partially diagrammatic, view of a trenching machine having a control system embodying the invention;

FIGURE 2 is a `diagram of the control system for the trenching machine shown in FIG. l;

FIGURE 3 is a diagram of an alternate control system suitable for an alternate standard type of trenching machine;

FIGURE 4 is a diagrammatic view of the valves and the control system shown in FIGURE 3; and

FIGURE 5 is a diagrammatic View of valves 51 and 52 shown in FIGURE 2.

While the invention will be described in connection with certain preferred embodiments, it will be understood that I do not intend to limit the invention to those embodiments. On the contrary, I intend to cover all alternatives, modifications, and equivalents which may be included within the spirit and scope of the invention as defined by the appended claims.

Turning first to FIG. 1, there is shown -a trenching machine having a control system embodying the present invention. The trenching machine includes a body 11 supported on crawler tracks 12 and having `a power plant 13. A digging mechanism in the form of a digging wheel 15 is mounted on a carriage 16 slidable on an upright frame 17. The frame 17 is pivoted at 18 to the body 11 so that it may be swung between a vertical operating position and a tilted transport position. To control the position of the frame 17, a tilting motor in the form of a double acting hydraulic actuator 19 is coupled between the body 11 of the trenching machine and the upper portion of the frame 17.

The carriage 16 is slid along the frame 17 by a hoist in the form of a single acting hydraulic actuator 20. The actuator 20, by vertically positioning the carriage 16, moves the digging wheel 15 into and out of contact with the surface being worked upon.

In order to dispose of di-rt or spoil removed by the digging wheel, a transverse conveyor 25 is disposed within the wheel so as to receive dirt removed during the digging operation. The conveyor 25 is driven by a motor 26 and, preferably, the conveyor is laterally adjustable and the motor 26 is reversible so that the conveyor can discharge dirt toward either side of the trenching machine.

In accordance with the invention, the motor 26 powering the conveyor 25 is driven at varying speeds by a single, iixed delivery, double pump through a control system embodying a simple directional valve and one flow control valve. In the preferred embodiment, best illustrat-ed in FIG. 2, this is accomplished by providing a double hydraulic pump 30 coupled to a reservoir or tank 31 and having rst and second fixed delivery ports 32 and 33, respectively. The iirst port 32 is coupled to the conveyor motor 26 by a line 34 through a reversing valve 35. The valve 35 is a four-way, three-position valve. When the valve is in neutral, fluid is passed from the line 34 to a return line 36 and the tank 31. When the valve 25 is shifted to its lirst position, fluid is directed from the line 34 through a line 37 so as to drive the motor 26 in one direction. When the valve 35 is shifted to its second position, iiuid is directed from the line 34 through a line 38 so as to drive the motor 26 in the opposite direction. When iluid is directed from the line 34 to the line 37, the valve 35 vents line 38 to the return line 36, 'and when fluid is directed through the line 38 tothe motor, the line 37 is vented to the return line 36.

The second pump discharge port 33 `is coupled by a line 41 through valves 51 and 52 to a diverter Valve 42 which is a three-way, three-position valve. The diverter valve is coupled to the reservoir return line 36 by a line 43 and to the motor 26 through a flow control valve 44. The valve 44 is of the xed orifice type that limits uid ilow toward the diverter valve 42 but which permits free ow from the diverter valve toward the motor 26.

When the -diverter valve 42 is in neutral position, iiuid from line 41 is passed through the valve to the line 43 and is returned to the reservoir or tank 31. Under this condition, the motor 26 is driven at an intermediate speed solely by the fluid discharge from the port 32.

When the diverter valve `42 is shifted to its first operative position, fluid is vented from the line 34 by coupling the flow control valve 44 to the return line 43. The motor 26 is thus driven at low speed since a portion of the fluid discharged from the port 32 is diverted from the motor through the flow control valve 44. The amount of fluid thus diverted, and hence the low speed of the motor 26, is determined by the setting of the ow control valve 44.

When the diverter valve 42 is shifted to its second operative position, the line 41 is opened to the valve 44 and hence the fluid from the port 33 is added to the iluid from the port 32 and both sources of fluid pressure act through the reversing valve 35 to drive the motor 26 at high speed. Since the valve 44 permits unrestricted fiuid flow from the diverter valve 42 to the motor 26,. the full hydraulic energy from the discharge port 33 is. effectively added to the energy from port 32 for driving; the motor 26.

For the purpose of controlling the frame tilt actuator 19 and the hoist actuator 2f), directional valves 51 and 52 are disposed between the diverter valve 42 and the second discharge port 33. The valve 51 is a three-way, threeposition valve coupled to the actuator 2% by a line 53.. When the valve 51 is in neutral position, the line 53 is blocked and the fiuid is passed freely from line 41 to the: adjacent valve 52. When the valve 51 is shifted to its first operative position, the line 41 is coupled to the line 53 and the hydraulic pressure causes the hoist actuator to slide the carriage 16 upwardly along the frame 17. Fluid, which may have leaked past the movable element of actuator 20, is discharged from the actuator through a line 55. When the valve 51 is shifted .to its second operative position, the line 53 is opened to the adjacent valve S2 and fluid is dumped `from the actuator 20 through line 45 to tank 31 so as to lower the carriage 16. Preferably, a fixed orifice, flow control valve 54 is interposed in the line 53 for restricting flow toward valve 51" so asto control the lowering rate of the actuator 20.

The valve 52 is a four-way, three-position 'val-ve conpled by lines 61 and 62 to the tilt actuator 19. When the valve 52 is in neutral position, the lines 61 and 62 are blocked and fluid from the line 41 is passed through the valve 52 to the diverter valve 42. When the valve 51 is shifted to its first operative position, the line 41E is opened to the line 61, and the line 62 is opened to the line 45 so that hydraulic pressure is applied to the actuator 19 to `tilt the frame 17 back over the body of the trenching machine.

When the valve 52 is shifted to its vsecond operative position, the line 41 is opened to the line 62 and the line 61 is Vented to the line 45 so that the actuator 19 shifts to the left in FIG. 2 and the frame 17 is moved to its upright position. In the illustrated embodiment, a flow control valve 63 is interposed in the line 61 so as -to control the rate at which the frame 17 moves to its upright position and thus balance the overhanging weight of the digging wheel 15.

Commercially available valves may be used in the disclosed hydraulic circuits. For valves 44, 54 and 63, Pneu-Trol fiow control valves part No. FCC-30008 manufactured by Pneu-Trol Devices, Inc., Chicago, Illinois, have proved satisfactory. Valves manufactured by Gresen Mfg. Co., Minneapolis, Minnesota, have proved satisfactory for reversing valve 35, diverter valve 42 and directional valves 51, 52. Reversing valve 35 may be Gresen valve part No. WP-DF4; diverter valve 42 may be Gresen valve part No. SP-D3; and valves 51, 52 may be Gresen valve part No. SPYT-3*4, which has a single body with two spool valves.

As a feature of the invention, the pump 3h provides a basic fiow of fluid for the actuators .19 and 2t) through discharge port 33 and a basic flow of fluid for motor 26 through discharge port 32. Diverting the iiuid iiow from port 33 to the motor 26 through Valve 42 increases the speed of the motor. Diverting fluid from port 32 through valve 44 decreases the speed of the motor. However, the relatively small volume of fluid being restricted by valve 44 does not result in any appreciable power loss in the system.

In utilizing the invention in a trenching machine which employs a ladder type digging mechanism rather than a digging wheel, the control system embodiment shown in FIG. 3 may be used. In illustrating and describing this embodiment, parts similar to those described above have been given the same reference numerals with the distinguishing suffix a added.

In the ladder type trenching machine, for which the control system shown in FIG. 3 is intended, the Aangular position of the digging ladder is controlled by a pair of tilting actuators 70 and 71. In addition, a hydraulic motor 72 is provided for shifting the spoil discharge conveyor from side to side.

In this embodiment, a line 41a runs from a double pump, not shown, to a diverter valve 42a. The diverter valve 42a is effective for adding hydraulic pressure through a flow control valve 44a to the conveyor motor, not shown, or for subtracting fiuid from the conveyor motor by venting the valve 44a to a return line 43a. Directional valves 51a and 52a are disposed between the line 41a and the diverter valve 42a, and are effective fo-r directing fluid through the lines 61a, 62a, and 53a, 55a, so as to control the actuators 76, 71 and the conveyor shift motor 72 respectively. In this embodiment both valves 51a and 52a are four-way, three-position valves. The operation of the control system of FIG. 3 is identical to the operation described above in connection with the FIG. 2 embodiment,

Itcan be seen'that the present invention provides a simple hydraulic control system capable of driving a hydraulic motor at a selected one of three separate speeds as well as providing power for a plurality of hydraulic actuators. The `system utilizes a single double pump having fixed delivery rates, a single flow control valve and :a simple diverter valve for adjustably controlling the ,speed of the conveyor motor. The use yof expensive variable delivery pumps or variable flow valves is avoided.

Furthermore, it will be noted that three-speed control of the conveyor results from adjustment of the diverter valve 42, vand that operation of the auxiliary actuators 19, 20 or 70, 71, and 72 is independent of the control of the motor V26 so that the auxiliary actuators can be operated without stopping the operation of the conveyor motor.

Having described the invention, what is claimed as new is:

l. A hydraulic control system for a trenching machine having a discharge conveyor comprising in combination, a hydraulic motor; a double hydraulic pump having first `and second delivery ports for hydraulic fluid; a first conduit means connecting said first delivery port to said motor for driving said motor at one speed; a second conduit means being selectively connectable between said second delivery port and said first conduit means through .a diverter valve, said diverter valve having first and seeond operative positions; said diverter valve when in said first operative position adapted to vent iiuid from said rst conduit means for driving said motor at a second speed; said diverter valve when in said second operative position adapted to add the flow of hydraulic fluid from said second delivery port to said rst conduit means for driving said motor at a third speed; and a ow control valve between said diverter valve and said first conduit means for limiting the flow of fluid toward said valve when in said first operative position.

2. A hydraulic control system for a trenching machine having a discharge conveyor, comprising, in combination, a hydraulic motor; a double hydraulic pump having first and second delivery ports for hydraulic fiuid; said first delivery port being Vconnected to said motor through a reversing valve for driving said motor at an intermediate speed in alternate directions; said second delivery port being connected to said reversing valve through a diverter valve; said diverter valve in one operative position adapted to direct uid from said second port to said motor to drive the motor at a speed above said intermediate speed; and a fiow control valve between said diverter valve and said reversing valve for limiting the fiow of fluid only from the reversing valve to the diverter valve so that said diverter valve in another operative position partially vents fluid from said reversing valve whereby the ow of fluid to said motor from said first port is reduced Causing the motor to be driven at a speed below said intermediate speed.

3. A hydraulic control systerrrfor a trenchingmachine having a discharge conveyor and a hydraulic actuating device comprising, in combination, a double hydraulic pump having first and second fixed delivery ports; a hydraulic motor; said rst port being coupled to said motor through a reversing valve for driving the motor at an intermediate speed in alternate directions; a diverter valve coupled to said second delivery port, said diverter valve also being coupled to said reversing valve and to a tank, said diverter valve adapted in one operative position to direct fluid from said second port to said motor through said reversing valve for driving said motor at a speed above said intermediate speed; a fixed orifice ilow control valve between said diverter valve and said reversing valve -for limiting the flow of iiuid only `from the reversing valve to the diverter valve whereby said diverter valve when in another operative position partially vents, liuid from the reversing valve reducing the flow of uid from said rst port causing the motor to be driven at a speed below said intermediate speed; and a directional valve between second delivery port and said diverter valve for selectively transmitting fluid to said hydraulic actuating device.

4. A hydraulic control system for a trenching machine having a discharge conveyor and a plurality of hydraulic actuating devices comprising, in combination, a double hydraulic pump having first and second fixed delivery ports; a hydraulic motor; said first port being coupled to said motor through a reversing valve for driving said motor at an intermediate speed in alternate directions; said second port being selectively connectable to said motor through said reversing valve; a diverter valve coupled between said second port and said reversing valve; said diverter valve also coupled to a tank, said diverter valve in one operable position adapted to direct fluid from said second port to said motor through said reversing valve yfor driving the motor at a speed above said intermediate speed; a Xed orifice How control valve coupled between said reversing valve and said diverter valve for limiting the ow of fluid from said first port means toward the diverter valve so that shifting the diverter valve to another operable position vents fluid from the reversing valve to the tank reducing the flow of fluid driving the motor from said rst port thus driving the motor at a speed below said intermediate speed; and a series of directional valves coupled between said second delivery port and said diverter valve for selectively transmitting fiuid to selected ones of said plurality of hydraulic actuating devices.

5. A hydraulic control system for a trenching machine having a discharge conveyor and a plurality of hydraulic actuators comprising, in combination, a hydraulic reservoir; a double hydraulic pump having first and second xed delivery ports; a hydraulic motor; said first port being coupled to said motor through a reversing valve for driving said motor at an intermediate speed in alternate directions; said second port being selectively connectable to said motor through said reversing valve; a diverter valve coupled between said second port and said reversing valve, -said diverter valve also coupled to said reservoir, said diverter valve adapted in one operable position to direct fluid from said second port to said motor adding to the flow tfrom said rst port for driving said motor at a speed above said intermediate speed; a fixed orifice ow control valve coupled between said reversing valve and said diverter valve for limiting the tlow of iiuid from said first port means toward the diverter valve, said diverter valve being further adapted in another operable position to vent fluid to said reservoir from said reversing valve whereby the iow of uid to said motor from said first port is reduced an amount determined by said ow control valve causing the motor to be driven at a speed below said intermediate speed; and a series of directional valves coupled between said second port and said diverter valve for selectively transmitting uid from said second port to selected ones of said plurality of hydraulic actuators; each of said series of directional valves being connected to selected ones of said hydraulic actuators and to said reservoir whereby said hydraulic actuators may be operated independently of operation of said motor.

References Cited in the tile of this patent UNITED STATES PATENTS 1,912,184 Ferris et al May 30, 1933 2,074,618 Roeder Mar. 23, 1937 2,254,708 Nye Sept. 2, 1941 2,276,895 Vosseler et al. Mar. 17, 1942 2,768,499 Pilch Oct. 30, 1956 2,879,612 Schultz et al. Mar. 31, 1959 

